In patent application Ser. No. 07/804,220, of even date herewith, entitled Electrothermal Printing Ink with Monodispersed Synthetic Pigment Particles and Method and Apparatus For Electronic Printing Therewith, a correlated novel printing ink is disclosed which offers superior image reproduction characteristics. The printing ink described in that application, the contents of which is hereby incorporated herein by reference, consists of a solid block of thermoplastic polymeric carrier material within which myriads of synthetic, monodispersed color pigments are embedded. These pigments of varied colors share essentially identical surface, bulk, and morphological properties, particularly their colorimetric and electrokinetic properties, in order to attain superior reproducible color representation in the printing materials obtained by that printing process.
The present invention concerns novel methods of controllably producing superior color pigments for that printing ink as well as for other coloration media through a series of manufacturing steps which lead to entirely predictable color values and surface charges for each and every pigment particle so as to achieve unprecedented manufacturing yield and quality of product. A variety of approaches to manufacturing these superior pigments is described by way of examples for the purpose of showing the broad basis of this invention.